Former Formula 1 driver Jenson Button, who won the world championship with Brawn GP in 2009, joins the Williams team on a multi-year deal with a remit to "support and develop both race and academy drivers", the company said in a statement.
Button will retain his role as a pundit with Sky Sports F1 for the coming season alongside his new role.
He will accompany the team at an unspecified number of Grand Prix as well as taking part in some events in the UK, while providing advice to the team at Grove.
"I am so delighted to once again be able to say that I’ve signed for Williams. Back when I was 19 it was a moment that changed my life and, despite the fact it was over 20 years ago, I already feel like I never really left," Button said.
"Sir Frank Williams showed faith in me which I will be eternally grateful for and I am incredibly excited to have the chance to come back and help the team as it strives once more for success. There’s a lot of hard work to be done but I have no doubt the future is incredibly bright for this fantastic team and I can’t wait to get started."
Incoming Williams Racing CEO Jost Capito, who replaces founder Sir Frank's daughter Clare Williams after the team was sold to US investors Dorilton Capital last year, said that the move was another positive step to revitalising the team's fortunes.
"Back in 2000, Sir Frank saw the promising talent Jenson had as a driver and gave him his first opportunity in F1. He more than fulfilled that initial promise throughout a glittering career that culminated in world championship glory," Capito said.
"More recently, he has shown his acumen in both the business and broadcasting worlds and remains a widely respected figure in the paddock. All this experience will add another layer to our transformation both technically and as a business."